Enameling



Patented May 4, 1926.

UNITED STATES PATENT OFFICE.

BARBIE G. PIERCE AND CHAD H. HUMPHBIES, OF KOKOMO, INDIANA, ASSIGNOBS T6 'UDYLITE PROCESS COMPANY, OF KOKOMO, INDIANA, A. CORPORATION 01 INDIANA.

ENAMELING.

No Drawing. I Application filed June 5, 1924. Serial No. 718,154. To all whom it may concern: fact that the treatment rendersenamels,

Be it known that we, HARRIE G. Prsnon' which otherwise can be easily flaked off, 65 and CHAD H. HUMrHnms, citizens of the firmly adherent, it has been noted that the United States, both residin at Kokomo, in metal surfaces, for instance bright cadmium 6 the county of Howard and tate of Indiana, plated surfaces, are considerably dulledby have invented certain new and useful Im the treatment. It has also been noted that provements in Enameling, of which the folin order to secure equal results a somewhat lowing is a specification. longer treatment with dilute solutions than Heretofore difficulty has been experienced with more concentrated solutions is required,

10 in the enameling of certain metallic surfaces and also that a sodium arsenate solution such as the electroplates of cadmium and when used hot gives the desired result more zinc, due to the fact that the enamels on quickly than when used cold, while the ef- 95 such surfaces after being baked show a fects of hot and cold solutions of sodiummarked tendency to flake off when sub phosphate appear to be practically equal.

jccted to light blows or even when scratched Articles dipped into either the phosphate with the finger na l. v solution or the arsenate solution and then The object of the present invention is the washed in hot water before being enameled provision of a process whereby this difgive fairly good results, although not as ficulty is overcome and the baked enamels good as when the dipped articles are per- 2 are rendered firmly adherent. mitted to dry without washing. Articles I The invention has particular reference to dipped into either solution and'then dried the enameling of cadmium coated articles can be washed for a considerablelength of and for convenience will be described in this time in boiling water without losing the connection. property imparted thereto by the action of 25 We have found that by subjecting cadthe solutions, but the dulled appearance as mium or cadmium plated surfaces to be well as the property of adhering to enamels enameled to the action of certain reagents a are removed by protracted washing of the good adherence of the baked enamel may be treated surfaces with boiling water. Very secured, and its tendency to flake off when satisfactory results are obtained by treating subjected to blows or abrasion is overcome. articles first with either of the solutions and Thus far in our investigations we have found then applying the enamel while the surfaces two materials capable of giving the desired are still we These observations give a results. These are sodium arsenate and sobasis for several theories as to the action dium acid phosphate (Na HPOQ While of the solutions upon the metal surfaces, the.

35 certain other materials which have been most likely of which seems to be that the tested, for instance, ferrous sulfate, have phosphates or arsenates react to some exgiven promising indications, none of them tent with the metals forming compounds have, as thus far tested, given satisfactory therewith in the form of a film which in results. We have therefore directed our at some way improves the adherence of the tention particularly to the use of the water enamels. Contrary to this theory, although soluble arsenates and the water soluble phosnot conclusively disproving it, is the fact phates, that is, to the oxygen compounds of that the phosphates and arsenates are used the elements in the right hand column in up very slowly and require practically no Group V of Mendelejeifs classification of replenishing.

' the elements, to wit, arsenic, phosphorus, The foregoing observations also indicate antimony and bismut the preferred procedure for treating metal The action of the phosphate and arsenates surfaces, which is as follows: upon the metal surfaces which resultsin the The metal articles to be enameled, for infirm adherence of the enamels thereto has stance, bright cadmium coated iron or steel not been definitely determined. The comarticles, are dipped into a solution of from pounds are applied by subjecting the metal 10 grams to 100 grams, preferably about 50 surfaces to relatively dilute and preferably grams, of sodium arsenate or sodium acid warm solutions thereof; Aside from the phosphate per liter at a temperature of should be thoroughly tions, but it is not necessary to 'maintain them in the solution for any prolonged period of time. With solutions of the concentrations indicated in the foregoing example it is only necessary to dip the articles and remove them immediately. However, if Very dilute solutions are used it is necessar in order to get the maximum effect to hold the articles in the bath for a short period of time. If solutions of greater concentration or at higher temperatures than those indicated in the foregoing example are used there is a tendency for the arsenate or phosphate to crystallize upon the surface of the articles. This does not apparently help or hinder the enameling, but of course is objegtionable in that it results in a waste of the sa ts.

Distilled or lime-free water should be used in preparing the phosphate solution in order to avoid the precipitation of calcium phosphate. 7

The effect of the treatment upon enameled articles is very striking. The enamels are distinctly more adherent than when the treatment is not employed, as may be found y comparative tests. The effect of the treatment is shown most clearly by dipping an article to be enameled only partly into the treating solution, drying it, and then coating it with the enamel. Before baking the enamel over the whole surface of the article appears'the same but after baking there is a clearline of demarcation between that part of the enamel on the treated portion of the article and the enamel on theuntreated portion. The enamel on the treated portion is darker and apparently smoother and more lustrous and is much more diflicult to remove either by striking or by scratchmg.

treating the same with an oxygen compound of one of the elements in the right hand column of Group V of Mendelejefs classificay tion of the elements and then applying enamel tothe treated surfaces.

2. In the process of enameling cadmium and zinc surfaces the steps which consist in treating the same with an aqueous solution of a soluble salt of an oxy acid of one of the elements in the right hand column of Group V of Mendelejeifs classification of the elements and then applying enamel to the treated surfaces.

3. Process of enameling cadmium and zinc surfaces which comprises contacting the same with a solution of an arsenate and thereafter applying enamel to the surfaces.

4. Process of enameling cadmium and zinc surfaces which comprises contacting the same with a solution of an arsenate, applying enamel to the surfaces, and baking the enamel.

5. Process of enameling bright cadimum coated articles which comprises treating the same with an oxygen compound of an element in the ri ht hand column of Group V of Mendelejeff s classification of the elements and applying enamel to the treated surfaces.

Process of enameling bright cadmium coated articles which comprises dipping the same into a warm solution of sodium arsenate, drying the wetted surfaces, and applying enamel thereto.

In testimony whereof, we aflix our signatures. I

HARRIE C. PIERCE. CHAD H. 'HUMPHRIES. 

